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How Sugar is Made

I find “raw” to be a pretty weird term for sugar, since all table sugars are “cooked” in a sense — boiled or heated to evaporate moisture. After that it’s mostly a matter of removing the “non-sugar” substances. But as usual I’m ahead of myself.

Sugar processing, as I mentioned below, starts by washing and pulping the sugarcane at a sugar mill. At that point the cane is pressed to remove the sucrose-heavy juice. The next step is to heat the juice to remove the moisture. Traditionally this was done by boiling, but since long-term boiling is both fuel-intensive and can destroy some of the flavors in the by-products (i.e. the molasses), most cane juice these days is “cooked” in vacuum pans which get the job done at a lower temperature. After many hours the juice turns thick and brown as the residual plant bits brown and some of the non-sucrose sugars caramelize. The finished product is a thick, very low moisture liquid called “dark brown” syrup.

The sucrose molecules in dark brown syrup are so crowded together that they start stacking up on each other as soon as the temperature gets low enough. Sugar crystals are of course the result. However because sugar refiners only want a crystals of a certain size and shape, they introduce “seed” crystals at this point to encourage formations that are uniform and thus easy to work with.

So far so good, yes? Now we get to the point at which the crystals are separated from, er…everything else. Traditionally as you know, the crystal soup was poured into tall, conical forms with holes at the bottom that allowed most of the non-sucrose liquids and solids to simply drain out (the result was an oblong “loaf” of sugar). Modern methods are similar, only the gravitational effect is heightened with the use of centrifuges, basically large rotating baskets lined with cloth. The crystalline mixture is, quite simply, spun. The fluid that spins out is of course molasses.

This fairly clear liquid still has quite a lot of sucrose in it, despite having undergone that initial crystallization process. So as not to waste any of it, refiners repeat the crystallization process. The resulting slurry is spun again. This time the molasses is quite a bit darker but still has some sucrose in it. So the crystallization and spinning process is repeated a third time, after which the molasses is, for all intents and purposes, black. As for the sugar, it hasn’t lost all of its molasses, even after all the spinning. It retains a thin coat which gives it a light brown color.

Processing up to this point usually happens at mills located very close to where the sugarcane is harvested, for once it’s cut, cane will start to ferment after just a few hours. Further processing is typically done somewhere else, usually in the more industrialized countries where the sugar ultimately sold. Of course it can be packaged and sold as-is, as a so-called “raw” product.

How “White” Sugar is, er…Further Made

“Raw” sugar is shipped wherever there’s a market for it. If that market is an industrialized nation, it’s usually further refined until it becomes the white, granulated sugar most of us know. The first thing that happens to the sugar is that a clear sugar syrup is added to turn it back into a slurry. At that point hot water is mixed in to melt everything back down again.

Why do this when the sugar miller went to so much trouble to evaporate and crystallize it in the first place? Because raw sugars not only contain “impurities” (i.e. molasses) the crystals are generally bigger and/or less uniform than sugar processors want. They need to be re-made before they can be sold as regular white sugar. However before that happens the last of the molasses — plant residues and a few more non-sucrose, long-chain sugars — need to be removed. To achieve that end the syrup is passed through a charcoal filter, which absorbs the various particles and clarifies the syrup.

Once that’s done it’s back to the vacuum pans to evaporate off the water that was added when the raw sugar first came to the refinery. Seed crystals that match the manufacturer’s specifications are added and the whole mess is sent through the centrifuges one last time. What emerges is a.) refined white sugar and b.) a lightly golden, so-called “refiner’s” or “cane” syrup.

So then what, in the end, is the difference between “raw” sugar and “refined white” sugar? Exactly one pass through a charcoal filter. That’s what separates “nutritious”, “whole” packaged sugar from “refined”, “white” packaged sugar. It’s never made sense to me, not even remotely. Yes, to vegans it matters, since the charred coal in the filters is frequently made from burnt bone meal, but these days there are non-animal derived filtration/clarifying techniques that can do the job (albeit more expensively).

Trust me, I ain’t lookin’ to start no fights. I’m just expressing my disbelief at how worked up people can get over a few tenths of a gram of molasses.

Where Brown Sugars Factor In

Brown sugars are something of a complicated subject, since they can be made at either the original sugar mill or at the refinery. As I put up examples I’ll try to make it clear which sugars come from which stage of the process. All of them, to a greater or lesser degree, are a mixture of crystal sugar and molasses.

At the mill a brown “raw” sugar can be derived from any of the different crystallization steps. At the refinery, brown sugar can be made in a couple of ways. The most common way is to simply melt the raw sugar with hot water and/or syrup, seed it and re-crystallize it as they do with white sugar, but allow it to retain the coating of molasses that it came with. The other way to do it is by “painting” the white sugar with molasses of varying hues (i.e. just mixing it with molasses). Most “dark brown” sugars are made this way.

A lot of people believe that the brown sugars that come from mills have purer, more interesting flavors than brown sugars made at the refinery. That may well be so. I’ve never done a side-by-side taste test since by and large I try not to get too obsessed with any single ingredient. The salt and olive oil fads, for example. Who has the time or money to get so absorbed? Anyway, there’ll be a lot more on this as I start putting up posts on the various types.

Sugar from Beets

A big technological advance in sugar making came along in 1747, when German chemist Andreas Sigismund Marggraf discovered a method for extracting sucrose from beets. That was a good thing for several reasons, chief among them that beets grow in a temperate climate, so sugar could be made close to home. Also, the sugar in beets doesn’t ferment as quickly as sugar in cane, so harvested beets can be stored for long periods before processing. Beet sugar became a very big thing in Europe from about 1800 onward. Only lately has beet sugar become a big deal in the States.

Beet sugar is made via a process similar to the one used for cane, save to say that the molasses isn’t nearly as tasty and is seldom used for baking in the manner that cane molasses is. Beet molasses does exist as a product in Europe. Here in America, however, it’s used as animal feed. Though most beet sugar is high quality, it occasionally carries a musty smell. For that reason when it comes baking and especially candy making, cane sugar should be preferred.

4 Responses to How Sugar is Made

I’m enjoying these entries on sugar and curious where piloncillo falls in the sugar making process. It seems to be like a cake (or cone as they usually sell it here in Mexico, although I have also seen it in little marble-sized balls) of raw brown sugar.